Watch the right search desperately for bad news on Obamacare

The peculiar efforts by opponents of the Affordable Care Act to knock down the unquestionably good news about its effects have continued this week, fueled by an omnibus survey released Tuesday by the Rand Corp.

We reviewed the report's findings here. The report, based on the latest poll of a group of respondents questioned by Rand every month, concluded that 9.3 million Americans gained health insurance between September 2013 and sometime in mid-March. It acknowledged that there's a built-in margin of error because of the survey size (roughly 2,400 individuals), and that its figure might change because sign-ups for 2014 were still continuing when polling ended, but it said that on the whole "the ACA has already led to a substantial increase in insurance coverage."

Cue the naysayers. They're led by Avik Roy of Forbes, one of the more assiduous ACA critics in the trade. Roy framed his report on the Rand study with the headline "RAND Comes Clean," thereby suggesting that it had been hiding something before issuing the report.

It turns out he's comparing the survey as issued to an advance report on it a week earlier by my colleague Noam Levey. Here's the rub: Levey reported that Rand found that one-third of exchange enrollees had been previously uninsured. The report placed that figure at 36%. (That's three points higher than one-third, if you're counting.)

So what did Rand "come clean" on? Its arithmetic, evidently, in which it calculates that 36% of its estimate of 3.9 million exchange enrollees in mid-March comes to ... (wait for it) 1.4 million. Of course, that's based on what Rand acknowledges are incomplete exchange enrollment figures; the states and federal government have estimated the ultimate sign-ups for the enrollment period ended March 31 (plus a couple of weeks of extensions) at more than 7 million.

Roy also wants to shave Rand's enrollment estimate by assuming that only "80 percent of signer-uppers will eventually pay their premiums," the ultimate validation of enrollment. He's placing his thumb on the scale a bit here, since his 80% estimate lowballs most published statistics. Charles Gaba of ACASignups compiled these, and the average looks to be more like 85%. That's the figure in California, too.

As Gaba has observed, at least some of the shortfall is likely due to the fact that the payment deadline for most people signing up late in the enrollment period had not even occurred before March 31, and bills may not even have been mailed out yet. So 85% may itself be a lowball figure.

One method used by Roy and James Taranto of the Wall Street Journal to knock down Rand's figures is to dismiss enrollments from sources other than the exchanges. (Taranto calls me a "cheerleader" for accepting the estimate of 7.1 million exchange enrollees produced by the White House and the states--and by Gaba--but if that's so, then I'm wielding the pom-poms right next to Avik Roy, who as recently as last weekend also accepted that figure, as seen in this clip from Fox News.)

Taranto and Roy cavil at the enrollments of previously uninsured people into Medicaid, which Rand calculated at 3.6 million of the 5.9 million total new Medicaid signups, as though for some reason they don't count. "Unsurprising," Taranto sniffs, "since Obamacare expanded that program and it is free to recipients." What of it? That's what it takes to get insurance to some uninsured Americans, and it was part of the ACA from the start.

The figure that really has ACA opponents vibrating is Rand's estimate of the growth in employer-sponsored insurance, or ESI--8.2 million since September, of whom 7.2 million were previously uninsured. This figure surprised everyone, because no one has been tracking this insurance category.

The naysayers' comeback is to question whether the ACA has anything at all to do with this growth. Rand doesn't fully explain it, but accepts that at least part of the increase is due to incentives created by the ACA, including the individual mandate. Rand doesn't think the increase is that big a deal, either, because the vast majority of Americans 18 to 64 get their insurance from ESI to begin with.

The weirdest challenge to the ESI figure comes from Ross Douthat of the New York Times, who speculated on Twitter that ESI enrollment must naturally jump each year after Sept. 30, when Rand started tracking insurance coverage.

His reasoning is that company open enrollments typically take place in the last quarter. But if he has some figures to back up his conclusion, let's see them; I couldn't find any reference in the literature on employer insurance to an annual enrollment spike at open-enrollment time. That's a time when employees renew or change their insurance, not usually when they sign up for the first time.